Ternary NiCoFe-layered double hydroxide hollow polyhedrons as highly efficient electrocatalysts for oxygen evolution reaction

正With exhaustion of fossil fuels and the deterioration of global environment,widespread and intensive researches have been concentrated on clean and sustainable alternative energy sources,such as metal-air batteries ~([1]),fuel cells ~([2]) and water splitting devices [3].Electrocatalytic oxidation of water to O_2 (oxygen     

Active facet determination of layered double hydroxide for oxygen evolution reaction

Oxygen evolution reaction(OER)plays an indispensable role in developing renewable clean energy resources.One of the critical bottlenecks for the reaction is the...     

Fe-doped Co_3O_4@C nanoparticles derived from layered double hydroxide used as efficient electrocatalyst for oxygen evolution reaction

Compared with noble metal catalyst, Co_3O_4-based electrocatalysts have attracted considerable interesting as low-cost alternatives for oxygen evolution reaction(OER). However, the poor electrocatalytic activity still remains a huge challenge. Herein, we demonstrate a feasible approach through oxidation of CoFe layered double hydroxide(CoFe-LDH) to synthesize Fe-doped Co_3O_4@C nanoparticles with size of about30–50 nm. As OER catalyst, the as-synthesized Fe-doped Co_3O_4@C nanoparticles exhibited superior OER performance with a small overpotential of 260 mV at the current density of 20 mA cm~(-2), a small Tafel slope of 70 mV dec~(-1) and long-term durability(there was no obviously OER current density degradation for 100 h) in alkaline solution. The present work opens a new avenue to the exploration of cost-effective and excellent electrocatalysts based on transition metal oxide materials to substitute precious metal materials for water splitting.     

Nickel iron carbonate hydroxide hydrate decorated with CeOx for highly efficient oxygen evolution reaction

Journal of Solid State Electrochemistry - Highly active, durable, and inexpensive nanostructured catalysts are crucial for achieving efficiently and economically electrochemical water splitting. In...     

Ternary layered double hydroxide oxygen evolution reaction electrocatalyst for anion exchange membrane alkaline seawater electrolysis

Anion exchange membrane(AEM) water electrolyzers are promising energy devices for the production of clean hydrogen from seawater. However, the lack of active and robust electrocatalysts for the oxygen evolution reaction(OER) severely impedes the development of this technology. In this study, a ternary layered double hydroxide(LDH) OER electrocatalyst(NiFeCo-LDH) is developed for high-performance AEM alkaline seawater electrolyzers. The AEM alkaline seawater electrolyzer catalyzed by the NiFeCo L...     

A novel composite electrode for oxygen evolution reaction

FeOOH nanowires were prepared and characterized with X-ray diffraction spectroscopy and scanning electron microscopy. A composite electrode consisting of FeOOH and Ni foam (FeOOH/Ni-foam) was fabricated, and its catalytic performance for oxygen evolution reaction (OER) was evaluated and compared with nanowire NiCo₂O₄/Ni-foam electrode. The mass current density of OER on FeOOH/Ni-foam is around three times of that on NiCo₂O₄/Ni-foam. Ni foam played a key role for the high activity of the FeOOH/Ni-foam. A synergistic mechanism of FeOOH and Ni was proposed to account for the superior catalytic performance of the FeOOH/Ni-foam electrode. Considering the low cost, abundant resource and environment-benign property of FeOOH, the FeOOH/Ni-foam electrode would be a promising anode for OER.     

Cu-alanine complex-derived CuO electrocatalysts with hierarchical nanostructures for efficient oxygen evolution

Nowadays,Cu-based materials have attracted extensive attention as electrocatalysts,while the inherent reason of the filling of high anti-bonding state of Cu d band(3 d~(10)4 s~1) makes it difficult to hybridize with O2 p band of oxygen intermediates during the adsorption process of oxygen evolution reaction(OER).To increase the efficiency of Cu-based electrocatalysts,efforts have been made to optimize the electronic structures and to create surface defects and hierarchical nanostructures with more exposed accessible active sites.Herein,we report a facile method for preparing CuO electrocatalysts with hierarchical nanostructures using the Cu-alanine complex as a precursor through room-temperature chemical precipitation and subsequent calcination in air.Investigations of products obtained at different calcination temperatures reveal the relationship between OER activities and the material characteristics such as specific surface areas,crystal growth orientations,and element components.The product obtained at 500℃ exhibits the smallest overpotential of 290 mV in 1.0 mol/L KOH for electrocatalyzing OER.Combining with various characterizations of CuO electrocatalysts after OER activities,the possible catalytic mechanism and the influence factors of their OER performance are also discussed.     

Single-crystalline layered double hydroxides with rich defects and hierarchical structure by mild reduction for enhancing the oxygen evolution reaction

The oxygen evolution reaction(OER) with sluggish reaction kinetics and large overpotential is the critical reaction in water splitting that is promising for energy storage and conversion. Layered double hydroxides(LDHs), due to their unique lamellar structure and flexibility of chemical component, are very competing material candidates for OER. Herein, the morphology structure and the electronic structure of LDHs were simultaneously tuned to improve the OER catalytic activity by mild solvothermal reduction using ethylene glycol. The increased surface area, the introduction of oxygen vacancies and the construction of hierarchical structure greatly enhanced the electro-catalytic activity of LDHs for OER. The as-prepared LDHs showed a lower over-potential as low as 276 mV at a current density of 10 mA cm~(-2), and a small Tafel slope of 40.3 mV dec~(-1) accompanied with good stability. This work provides an efficient way to the design and optimization of advanced catalysts in the future.     

Facile synthesis of thin NiFe-layered double hydroxides nanosheets efficient for oxygen evolution

Ultrathin NiFe-layered double hydroxide (LDH) nanosheets are facilely and cost-effectively fabricated. The as-prepared NiFe-LDH nanosheets are highly active and stable electrocatalysts for water oxidation in alkaline environment, exhibiting a much higher oxygen evolution activity and lower overpotential with the enhanced stability, much superior to the previously reported LDH-derived catalysts. This work provides a facile methodology for the fabrication of thin nanosheets, which are promising in the renewable energy conversion.     

Electrodeposition of cobalt-sulfide nanosheets film as an efficient electrocatalyst for oxygen evolution reaction

In this communication, we report the development of cobalt-sulfide nanosheets film on Ti mesh (Co-S/Ti mesh) via electrodeposition as a novel oxygen evolution anode in basic media. Electrochemical experiments suggest that this Co-S/Ti mesh electrode exhibits high catalytic activity and good stability. It needs overpotential of 361 mV to drive current density of 10 mA cm^− 2 and its catalytic activity is maintained for at least 20 h.     

Heterostructured FeNi hydroxide for effective electrocatalytic oxygen evolution

Hydrogen production technology by water splitting has been heralded as an effective means to alleviate the envisioned energy crisis. However, the overall efficiency of water splitting is limited by the effectiveness of the anodic oxygen evolution reaction (OER) due to the high energy barrier of the 4e⁻ process. The key to addressing this challenge is the development of high-performing catalysts. Transition-metal hydroxides with high intrinsic activity and stability have been widely studied for this purpose. Herein, we report a gelatin-induced structure-directing strategy for the preparation of a butterfly-like FeNi/Ni heterostructure (FeNi/Ni HS) with excellent catalytic performance. The electronic interactions between Ni²⁺ and Fe³⁺ are evident both in the mixed-metal “torso” region and at the “torso/wing” interface with increasing Ni³⁺ as a result of electron transfer from Ni²⁺ to Fe³⁺ mediated by the oxo bridge. The amount of Ni³⁺ also increases in the “wings”, which is believed to be a consequence of charge balancing between Ni and O ions due to the presence of Ni vacancies upon formation of the heterostructure. The high-valence Ni³⁺ with enhanced Lewis acidity helps strengthen the binding with OH⁻ to afford oxygen-containing intermediates, thus accelerating the OER process. Direct evidence of FeNi/Ni HS facilitating the formation of the Ni–OOH intermediate was provided by in situ Raman studies; the intermediate was produced at lower oxidation potentials than when Ni₂(CO₃)(OH)₂ was used as the reference. The Co congener (FeCo/Co HS), prepared in a similar fashion, also showed excellent catalytic performance.

A butterfly-like FeNi/Ni HS featuring a “torso” of Ni-doped FeOOH and two “wings” of Ni₂(CO₃)(OH)₂ showed excellent activity in electrocatalytic oxygen evolution reaction attributable to the increase of higher-valance Ni³⁺ in the heterostructure.     

NiFe水滑石纳米片阵列负载Ru用于提升碱性电催化析氢和析氧性能

通过离子交换的方式将Ru负载到NiFe水滑石(LDH)纳米阵列表面得到(Ru/NiFe LDH),Ru的引入显著提升了NiFe LDH的活性比表面积,暴露了更多的活性位点,同时调控了其电子结构,大大提升了其本征催化活性。在碱性条件下,催化析氢反应时仅需50 mV的过电位即可达到10 mA·cm^-2的电流密度,Tafel斜率为52.3 mV·dec^-1。而相同条件下原始NiFe LDH达到10mA·cm^-2的电流密度则需要226 mV的过电位,Tafel斜率为157.5 mV·dec^-1。同时制备的Ru/NiFe LDH也展现出了良好的析氧催化活性,在50 mA·cm^-2的电流密度下,过电位仅为231 mV,而NiFe LDH则需237 mV。Ru/NiFe LDH在长时间的电催化条件下依然能保持良好的工作稳定性。     

NiFe水滑石纳米片阵列负载Ru用于提升碱性电催化析氢和析氧性能

通过离子交换的方式将Ru负载到NiFe水滑石（LDH）纳米阵列表面得到（Ru/NiFe LDH）,Ru的引入显著提升了NiFe LDH的活性比表面积,暴露了更多的活性位点,同时调控了其电子结构,大大提升了其本征催化活性。在碱性条件下,催化析氢反应时仅需50 mV的过电位即可达到10 mA·cm^-2的电流密度,Tafel斜率为52.3 mV·dec^-1。而相同条件下原始NiFe LDH达到10mA·cm^-2的电流密度则需要226 mV的过电位,Tafel斜率为157.5 mV·dec^-1。同时制备的Ru/NiFe LDH也展现出了良好的析氧催化活性,在50 mA·cm^-2的电流密度下,过电位仅为231 mV,而NiFe LDH则需237 mV。Ru/NiFe LDH在长时间的电催化条件下依然能保持良好的工作稳定性。     

Anion engineering of hierarchical Co-A (A = O,Se, P) hexagrams for efficient electrocatalytic oxygen evolution reaction

Water electrolysis is considered to be an effective and promising technology to make high-purity H₂, however, the relationship between anion species and catalytic performance of electrocatalysts is still not completely clear. Herein, we report an anion engineering strategy to tune electrocatalytic water oxidation activity for Co-based materials. Novel hierarchical Co-based oxide/selenide/phosphide (Co-A, A = O, Se, P) hexagrams have been chosen as model materials. Electrochemical results and theoretical calculations reveal that the electron configuration, the electrical conductivity, and the oxidation potential of Co element in Co-A hexagrams could be moderated by the substitution of P atoms, which leads to the superior OER performance. Particularly, Co-P hexagram displays a low overpotential (η = 269 mV) at j = 10 mA/cm² for the oxygen evolution reaction (OER) compared to Co-O hexagram (η = 399 mV) and Co-Se hexagram (η = 347 mV). This work is of great importance in understanding coordination atoms (O, Se and P) induced electrocatalytic properties of hierarchical Co-based materials.     

CoP@SiO2nanoreactors: A core-shell structure for efficient electrocatalytic oxygen evolution reaction

Metallic phosphides as a crucial class of metal-like compounds show high electric conductivity and electrochemical properties. It is of significant benefit to understanding the relationship between the electrocatalytic performance and phosphating degree of precursors. In this work, using Co₃O₄@SiO₂ as precursor, core-shell structured CoP@SiO₂ nanoreactors with outstanding oxygen evolution reaction performance were synthesized through a facile calcination method. The electrocatalytic performance of CoP@SiO₂ modified electrode that treated with 500 mg NaH₂PO₂ was greatly enhanced. The obtained product displays a low overpotential of 280 mV at a current density of 10 mA/cm² and a Tafel value 89 mV/dec in alkaline conditions. The easy available CoP@SiO₂ with outstanding catalytic performance and stability possesses huge potential in future electrochemical applications.     

Ni3S2@NiFePx electrode with dual-anion-modulated layer for efficient and stable oxygen evolution

The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction (OER) is a prerequisite for efficient water electrolysis. Herein, we develop a broccoli-like Ni₃S₂@NiFeP_x (Ni₃S₂@NFP) catalyst on nickel foam (NF) via a sequential two-step layer-by-layer assembly electrodeposition method. X-ray diffraction, in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition. The reconstruction of double layer Ni₃S₂@NFP facilitates the formation of the active (oxy)hydroxides, which is modulated by the dual anionic layer with mixed sulfate and phosphate ions. As a result, the obtained Ni₃S₂@NFP electrode exhibits low overpotential (329 mV) and long-term durability (∼500 h) for OER at current density of 500 mA/cm². Moreover, the self-supported Ni₃S₂@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device (AEMWE). This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance.     

具有高效析氧催化性能的铁基双元金属有机框架纳米棒研究

析氧反应(OER)是电解水制氢的关键步骤,开发高效、稳定、廉价的OER电催化剂是目前该领域的研究热点.碱性电解液中的OER电催化剂成分以Mn、Fe、Co、Ni等为主,其中单一组分的Fe基化合物催化活性不高,但碱性电解液中的痕量铁杂质极易掺入Ni、Co等非Fe基材料的结构中,极大影响其OER催化性能,即现有大部分非Fe基...     

Manganese oxide with hollow rambutan-like morphology as highly efficient electrocatalyst for oxygen evolution reaction

The research about oxygen evolution reaction (OER) has attracted extensive attention. In this work, different manganese oxides with different shell thickness were firstly grown on the surface of carbon ball template, and then the carbon ball was removed by high-temperature calcination in air to obtain hollow rambutan-like Mn₂O₃ and MnO₂–Mn₂O₃ with long nanowires. The concentration of inorganic manganese salt and the reaction time has a determining influence on the morphologies of manganese oxide. The as-prepared MnO₂–Mn₂O₃ exhibits a lower overpotential than the Mn₂O₃ to achieve a current density of 10 mA cm^?2. The Faradic efficiency of MnO₂–Mn₂O₃ reaches to 94.1% during the bulk electrolysis, and the morphology of MnO₂–Mn₂O₃ remains virtually unchanged after electrolysis, indicating the outstanding stability of the as-obtained MnO₂–Mn₂O₃.     

Highly efficient electrocatalysts for oxygen reduction reaction

Highly efficient and chemically compatible LnxSr1-xCoO3-delta (Ln = La, Sm, Gd, ...)/Co3O4 electrocatalysts for oxygen reduction reaction are presented and the very low cathode polarization resistances and excellent performances implied their promising application for developing intermediate-temperature solid oxide fuel cells (SOFCs), as well as potential application for oxygen separation membranes.